Rubber compositions for tire sidewalls typically include various elastomers and may be reinforced with, among other things, carbon black. Carbon black imparts such beneficial properties as abrasion resistance and electrical conductivity. For some applications, however, it may be desirable to reduce the carbon black content of the sidewall to reduce the sidewall's hysteresis. The hysteresis of a rubber composition is a measure of the rubber composition's tendency to generate internal heat under service conditions. Hysteresis is a term for heat energy expended in a material, such as, for example, a cured rubber composition, by applied work. A lower hysteretic tire sidewall rubber layer promotes lower rolling resistance, lower heat build-up for the respective tire, or both. Typically, a low “tan δ” and an increase in the rubber composition's rebound value are indicative of reduced hysteresis of the rubber composition. Tan δ is a measure of the rubber composition's heat build-up.
While low hysteresis may be a desirable quality in tire sidewall compositions, reduced carbon black content may result in a lower compound modulus.
The present embodiments relate to reduced hysteresis silica-containing black sidewall compounds having increased toughness properties and methods for preparing the same. Tires comprising the black sidewall compounds prepared according to the present embodiments are also provided.